ANALYSIS OF LINKAGE POSITIONS IN 2-ACETAMIDO-2-DEOXY-D-GLUCOPYRANOSYL RESIDUES BY THE REDUCTIVE-CLEAVAGE METHOD

Article abstract of DOI:10.1016/0008-6215(86)85064-9

The fate of methylated 2-acetamido-2-deoxy-D-glucopyranosyl residues under reductive-cleavage conditions was investigated by using methyl 2-(acetylmethylamino)-2-deoxy-3,4,6-tri-O-methyl-β-D-glucopyranoside (1), its α anomer (8), and fully methylated lacto-N-tetraitol as test compounds.Treatment of 1 with triethylsilane and trimethylsilyl trifluoromethanesulfonate in dichloromethane gave rise to (1,2-dideoxy-3,4,6-tri-O-methyl-α-D-glucopyrano)-2,3-dimethyl-<2,1-d>-2-oxazolinium trifluoromethanesulfonate.Quenching of the reaction by addition of aqueous sodium hydrogencarbonate resulted in hydrolysis of the oxazolinium salt.Compound 8 was fully stable to reductive-cleavage conditions.Thus, participation by the 2-acetamido group is necessary for glycosidic carbon-oxygen bond-cleavage to occur.Treatment of methyl 2-deoxy-2-(ethylmethylamino)-3,4,6-tri-O-methyl-α,β-D-glucopyranoside under reductive-cleavage conditions resulted in some anomerization, but neither hydrolysis nor reductive cleavage of the glycosidic carbon-oxygen bond was observed, as expected.Reductive cleavage of fully methylated lacto-N-tetraitol gave the products predicted on the basis of these and prior model studies, including 3-O-acetyl-2-(acetylmethylamino)-2-deoxy-4,6-di-O-methyl-D-glucopyranose derived from the 3-linked 2-acetamido-2-deoxy-β-D-glucopyranosyl residue.